1. Field of the Invention
The present invention relates to an impact type printer and more specifically to device for controlling the printing pressure with which type is impacted against a recording paper through an ink ribbon. In particular, the present invention is directed to improvement in the quality of print by controlling the printing pressure according to the kind of ink ribbon then used in the printer.
2. Description of the Prior Art
For the impact type printer there are known and used two types of ink ribbons one of which is of multi-strike type and the other is of correctable type. The multi-strike type ink ribbon is adapted for repeated use by being struck many times. To this end, it has a relatively thick ink layer coated on one surface of a substrate at high density. In contrast, the correctable ink ribbon has a relatively thin ink layer so that the ink once printed on the recording paper can be lifted off through an erasing ribbon to correct a printing error.
There are also known those typewriters in which these two different types of ink ribbons can be used selectively and interchangeably. However, the known typewriters have a common important drawback. When the multi-strike type ink ribbon is used, these typewriters can not produce any high quality print. The character printed through the multi-strike ink ribbon is too thick to be legible. Every line of a character or symbol is too heavy and fat. The letters printed by the multi-strike ink ribbon therefore lack sharpness and are poor in print quality.